1# http://www.gnu.org/software/make/manual/make.html#Syntax-of-Functions
 2,:= ,
 3empty:=
 4space:= $(empty) $(empty)
 5foo:= a b c
 6bar:= $(subst $(space),$,,$(foo))
 7# bar is now `,abc'
 8# space in `,$(foo)' replaced with `$', which will be empty
 9
10test:
11	echo $(bar)